Brake-cylinder



, (No Model.)

I 2 Sheets-Sheet 1'. F. L. CLARK. BRAKE CYLINDER.

No. 574.665. Patented Jan. 5, 1897.

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F. L. CLARK. BRAKECYLINDBR.

10,574,665.' Patented Jan. 5', 18,97.

UNiTnDV STATES PATENT OFFICE.

FRANCIS CLARK, OF STEWART STATION, PENNSYLVANIA.

BRAKE-CYLINDER.

SPECIFICATION forming part of Letters Patent No. 574,665, dated January 5, 1897.

Application led September 1 9, l 8 9 6.

vTo all whom t may concern:

Be it known that I, FRANCIS L. CLARK, of Stewart Station, in the county of Westmoreland and State of Pennsylvania, have invented a certain new and useful Improvement in Brake-Cylinders, of which improvement the following is a specification.

My invention relates more particularly to cylinders of brake apparatus of the class in which the application of the brake-shoes to the wheels is eifected by hydraulic pressure, but is also applicable, without variation of operative principle or essential structural clements, to other mechanisms in which the eX- ertion of hydraulic pressure is effected.

The object of my invention is to provide means whereby the pressure of water or other incompressible iiuid may be exerted upon the brake-shoes or other movable members, through pistons and intermediate connections, in' such manner as to preliminarily take up the slack of the connections and impose an initial strain thereon, by the action of a comparatively small quantity of actuating fluid upon a piston, and thereafter to hold said liuid under the applied pressure 'and apply the greater final pressure required by the action of fluid upon a larger piston of comparatively short traverse, thereby attaining` large braking or compressing force with a material economy of actuating huid.

To this end my invention, generally stated, consists in the combination of two cylinders of dilferential areas of transverse section, pistons fitted therein, two movable pressure members, connections coupling the pistons one to the other and to the pressure members, and a valvular mechanism controlling` the flow of fluid in sequence to and from said cylinders.

The improvement claimed is hereinafter fully set forth.

In the accompanying drawings, Figure 1 is a view, partly in elevation and partly in section, of a brake-applying mechanism illustratingan application of my invention; Fig. 2, a longitudinal central section, on an enlarged scale, through the valvular mechanism thereof; Fig. 3, a similar section through the' slide-valve when in application position; Fig. 4, a diagrammatic view illustrating the application of the apparatus in connection with Serial No. 606,319. (No model.)

four brake-shoes and Fig. 5, a View, partly in elevation and partly in section, illustrating the application of the invention in actuating the platens of a press.

In the practice of my invention, referring, first, to Figs. 1, 2, and 3, I provide two cylinders 1 2, of smaller and larger diameters, respectively, which are connected one to the other and to an interposed head 1 in line axially. The cylinder 1 is fitted with a properly-packed piston 13, which is secured upon a piston-rod 14, and the cylinder 2 is fitted with apacked piston l5,which is secured upon a piston-rod 16. The pistons 13 and 15 are normally held in release posit-ion, that is, a short distance from the interposed common cylinder-head l, by springs 21 and 22, which surround the piston-rods 14 and 16, respectively,and are returned by said springs to said position upon the release of pressure from the apparatus, as presently to be described. The piston-rods 14 and 16 are connected to the upper ends of brake-levers 17 and 17a, respectively, the lower ends of which are connected by a brake-rod 18, and the brake-levers 17 17 are connected between their ends to brake-shoes 19, which are supported by hangers 2O upon the frame or truck of a car.

Actuating iuid, which may be water containing material of such character as will prevent freezing or any other suitable incompressible-huid medium, is supplied to and released from the cylinders 1 and 2 by a valvular mechanism litted in a casing 4, which communicates with a force-pump or other source of pressure by a pipe 3 and with the cylin ders 1 and 2 between their pistons and the head 1a by pipes 5 and 6, respectively. The port-openings of the pipes 3 and 6 in the casing 4 are controlled by a slide-valve 7, having a recess or cavity 7b in its face and a port 7:L extending through it near one of its ends. The slide-valve 7 is connected to a stem 8, upon which are fixed differential pistons 9 and l0, the larger piston 10 fitting a cylindrical chamber in the casing 4 and the smaller piston 9 itting a cylindrical bore in a remov- IOO are normally held in the release position, as shown in Figs. 1 and 2, by a spring 11,which fits in a cylindrical extension i of the casing l and bears against the stem S and against a head 11b, which abuts against the end of an adjusting-screw 11", by which the tension of the spring 11 may be varied as desired. The spring-casing et is connected detachably t the casin g 1 by a union 4b, and when removed admits of the insertion and removal of the larger valve-piston in and from the casin g in which it works.

In operation actuating fluid from a pump or other source of supply enters the casing t of the valvular mechanism through the pipe 3 a-nd passes through the port 7, the chamber of the valve 7, and the pipe 5 to the cylinderl, forcing the piston 13 thereof outwardly until the slack of the connections between said pistons and the movable pressure members (which are in this case the brake-shoes 19) and the spaces between said shoes and the treads of the wheels have taken up, thereby bringing the shoes into contact with the wheels and imposing an initial strain upon the connections. This will be effected at or before the time the piston 13 reaches a shoulder in its cylinder which acts as the limit of its outward traverse, unless there be a greater amount of slack to be faken up in the first instance, in which case the excess will be taken up by the piston of the larger cylinder, and thereafter such preliminary work will be done exclusively by the smaller piston. In the construct-ions ordinarily heretofore employed this operation requires a comparatively long traverse of a piston of sufficiently large diameter to exert the required final braking force, and consequentlyinvolves the supply of a correspondingly large volume of fiuid, while under my improvement a much smaller volume suffices to actuate the piston 13 of the smaller cylinder, by which this preliminary function is performed.

The space between the piston of the larger cylinder 2 and the head l, the pipe 6, leading to said cylinder, and the recess 7 of the valve 7 are, it should be noted, filled with fiuid, which, being incompressible and having no outlet, acts as an abutment for the piston 15, and consequently in the outward traverse of the smaller piston 13 the pin 1G, by which the brake-lever 17 is coupled to the rod of the. larger piston, acts as the fulcrum of the brake-levers.

XVhen the pressure in the smaller cylinder 1 reaches a predetermined degree, controlled by the tension of the spring 11, the valvepistons 9 and 10 are moved to the right by the pressure of the actuating fluid upon the excess area of the larger piston 10, assisted by the pressure of the piston 15 of the larger cylinder 2 upon the fluid within said cylinder, which pressure is transmitted to the outer face of the smaller valve-piston fl through the pipe 6, the recess 7b of the valve 7, and a port 12, leading from the face on which said valve traverses to the outer side of the piston 9. In the preliminary traverse of the valve 7 said valve uncovers the port 12, thereby cutting off the flow of fluid from the larger cylinder to said port. The valve is traversed farther to the right until the bridge between the valveport 7 L and the recess 7b cuts off communication between the pipe 3 and the valve-chamber and opens, slightly, communication between the pipes 3 and G through the recess 7b. The final traverse of the valve to the position shown in Fig. 3 is effected by the reaction of the fluid in the smaller cylinder l on thelargervalve-piston l0 through the pipe 5. The actuating fluid from the pipe 3 passes through the valve-recess 7 b and pipe G into the larger cylinder 2 and effects the final application of the brakes with maximum force by its pressure upon the piston 15 of said cylinder. During the action of said piston the escape of fluid from the smaller cylinder 1 cut off by the valve 7, and the fluid in said cylinder acts as an abutment for the piston 13. Consequently in the outward traverse of the larger piston 15 the pin 11, by which the brake-lever 17 is coupled to the rod of the smaller piston, acts as the fulcrum of the brake-levers.

In effecting an application of power from the pistons to the brake-shoes or other equivalent connected movable pressure members the pressure rises in the respective cylinders inversely to their diam eters. That is to say, assuming the areas to be as five to one when actuating fluid is applied to the smaller piston and the pin of the piston-rod of the larger cylinder acts as the fulcrum the pressure in the larger cylinder rises as one to five, or five pounds per square inch on the smaller piston produces a pressure of one pound per square inch on the larger piston. lhen pressure is applied to the larger piston and the pin of the piston-rod of the smaller cylinder acts as the fulcrum, the pressure in the smaller cylinder rises as five to one, or one pound per square inch on the larger piston produces a pressure of five pounds persquare inch on the smaller piston.

To effect the release of pressure from the brake-shoes or other movable pressure members, the pressure of actuating fluid in the pipe 3 is released and 'fluid thereupon flows from the larger cylinder 2, through the pipe G and the valve-recess 7b, to the pipe As soon as the pressure is reduced to a point such that the pressure in the smaller cylinder 1 falls below the tension of the spring 11 said spring returns the valve-pistons 9 and 10 and the valve 7 to the release position shown in Figs. 1 and 2, and there then being an outlet from the smaller cylinder the spring 2l returns the piston thereof to the posit-ion shown in said figures. The ret urn of the larger piston is eected bythe strain on the connections which forces out the liquid until the pressure is reduced to that which was exerted .when the valve closed communication be- IOO IIO

tween the pump and the larger cylinder. There will be a degree of pressure retained in the larger cylinder, by reason of the closure of the pipe 6 by the valve 7, equal to that which was exerted therein before its piston received any pressure from that of the smaller cylinder.

Inasmuch as the valve 7 closes communication between the pipes 6 and 3 at the time when the pressure in the larger cylinder is equal to that which Was exerted in said cylinder when pressure was admit-ted to the smaller cylinder, there is always sufficient pressure in the larger cylinder to take up a preliminary excess of slack above that which may have been provided for by the extreme traverse of the smaller piston and such additional slack as may be caused by each successive'application of the brake-shoes to the wheels. The larger piston will consequently gradually move farther from the head 1 and a correspondingly larger volume of fluid be retained in said cylinder when the piston thereof is in release position as the brakeshoes Wear out; but the length of traverse of said piston in each application will remain invariable. l/Vhen the brake-shoes are worn out or the piston of the larger cylinder has moved so far out as not to admit of farther traverse, the liquid remaining in the larger cylinder between the piston 15 and the head 1n is drawn off andthe piston returned to normal position. A suitable cock (not shown) is provided for this purpose in the larger cylinder, and the pipe governedby said cock is preferably led to the reservoir or source of fluid-supply.

Fig. 4 illustrates the application of my invention as applied in actuating four brakeshoes, and also shows the brake-shoes as connected to secondary brake-levers 23, instead of being directly connected to the brake-levers 17 17 a, as first described. The secondary levers 23 are coupled one to the other by brake-rods 24: and to the primary brake-levers by brake-rods 25. The operation and the essential structural elements are identical with the corresponding features of the construction of Figs. 1, 2, and 3, and it will be seen that a correspondingly greater economy. of 'liuid is attained where, asin constructions of the general character of that shown in Fig. 4, the leverages are increased and a greater degree of slack in the connections is required to be taken up.

As illustrated in Fig. 5, the movable pressure members are applied as the platens 19fL of a press, and are coupled by links 19b to levers 17 17 il, which are connected one to the other by a rod 18 and connected to the piston-rods 14 and 16 of a mechanism similar in all essential particulars of construction to that shown in Figs. 1, 2, and 3 and lhereinbefore described.

Iclaim as my invention and desire to secure by Letters Patent- 1. In a mechanism for applying hydraulic pressure, the combination, substantially as set forth, of two cylinders of differential areas of transverse section, pistons tted therein, two movable pressure members, connections coupling the pistons one to the other and to the pressure members, a pipe for the supply and release of incompressible iiuid under pressure, and a valvular mechanism, controlling, in sequence, the retention of fluid in the larger cylinder to act as an abutment for the smaller piston, the ilow of Huid to the smaller cylinder, the retention of fluid in the smaller cylinder to actas an abutment for the larger piston, and the flow of liuid to the larger cylinder.

2. In a mechanism for applying hydraulic pressure, the combination, substantially as set forth, of two cylinders of differential areas of transverse sections, pistons fitted therein, two movable pressure members, connections coupling the pistons one to the other and to the pressure members, a pipe for the supply and release of fluid under pressure, a valve controlling communication between said pipe and the larger cylinder,and between said pipe and the smaller cylinder, two differential pistons connected to said valve and subject to the pressure in the fluid supply and release pipe, and a spring acting on said pistons in direction opposite to that of the action of fluid-pressure upon the larger thereof.

3. In a hydraulic-pressure brake mechanism, the combination, substantially as set forth, of two brake-cylinders of differential areas of transverse section, pistons fitted therein, piston-rods secured to said pistons and projecting in opposite directions from the cylinders, brake-levers coupled to said pistonrods, a brake-rod cou ling said brake-levers one to the other, brake-shoes coupled to said brake-levers, a pipe for the supply and release of incompressible fluid under pressure, and a valvular mechanism,controlling,in sequence, the retention of fluid in the larger cylinder to act as an abutment for the smaller piston, the flow of liuid to the smaller-cylinder, the retention of iiuid in the smaller cylinder to act as an abutment for the larger piston, and the flow of liuid to the larger cylinder.

4. In a hydraulic-pressure brake mechanism, the combination, substantially as set forth, of an initially-operating brake-cylinder and piston, a finally-operating brake-cylinder and piston of larger diameter, two oppositelyacting brake-shoes, connections coupling the brake-cylinder pistons one to the other and to the brake-shoes, a valve-casing having connections to a pipe for the supply and release of fluid under pressure and to the larger and the smaller brake-cylinders, a controllingvalve traversing in said casing` and having a port adapted to establish communication between the fluid-pressure pipe and the smaller cylinder, and a recess adapted to establish communication alternatelybetween the larger cylinder and the outer face of the smaller differential valve-piston hereinafter specied,

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and between the larger cylinder and the lluidpressure pipe, two differential pistons connected to the controlling-valve and subject on their adjacent faces to the pressure in the fluid-pressure pipe, a port controlled by said Valve and leading from the inner to the outer face of the smaller valve-piston, and a spring,r acting on the Valve-pistons in direction opposite to that of the action of fluid-pressure on the larger thereof.

5. In a hydraulic-pressure brake mechanism, the combination, substantially as set forth, 0f two brake-cylinders of different diameters, pistons fitted therein, two brakeshoe connections coupling` the pistons one to the other and to the brake-shoes, and a valvular mechanism actuated by oppositely-exerted lfluid and spring.;` pressures, through which FRANCIS li. CLARK.

lVitnesses:

CHAs. A. HUNTER, GEO. B. MEANOR, Jr. 

